My idea shows how to quickly fix broken edgefinders using a paper clip and a 6-in. scale.
Myrtle Beach, S.C.
Making inaccurate machines accurate
Some economy-model lathes are notoriously inaccurate. Stick-slip of their dovetail or V-style slides and feedscrews make controlling longitudinal feeds (carriages) and cross feeds difficult using the available handwheels and vernier scales. I eliminate these shortcomings and achieve repeatable diametric accuracies of 0.0002 in. and bore depths within 0.001 in. by clamping a dial indicator to the lathe bed and one to its cross slide.
For meeting the lathe-bed indicator's point, I attach a target at a convenient spot, and both the indicator and target are longitudinally adjustable. The cross-slide indicator's point rides against the machine's tool post. A magnetic mounting clamp holds this indicator in place and makes it adjustable along a custom-made rod mounted to the machine carriage.
As a secondary control tool, I mount an industrial limit switch to the lathe's bed clamp and its adjustable target to the small shelf located under the carriage that holds the indicator's target. I wire the limit switch's normally closed contacts to the machine's "run" relay wiring with cable. An in-line, on-off switch serves as an override that delivers power to the machine spindle for finishing shoulders or bore bottoms. The setup also lets me turn long shafts unattended because the machine automatically shuts off at the end of the run.